RTT::DataObjectLockFree< T > Class Template Reference
[Data Transfer Ports]

This DataObject is a Lock-Free implementation, such that reads and writes can happen concurrently without priority inversions. More...

#include <rtt/DataObjectInterfaces.hpp>

Inheritance diagram for RTT::DataObjectLockFree< T >:

List of all members.

Public Types
typedef T	DataType
	The type of the data.
typedef boost::intrusive_ptr < DataObjectInterface< T > >	shared_ptr
	If you plan to use a reference counted DataObject, use this type to store it and apply this->deref() to enable reference counting.
typedef DataSource< T >::value_t	value_t
	The bare type of T is extracted into value_t.
typedef boost::call_traits < value_t >::param_type	param_t
typedef boost::call_traits < value_t >::reference	reference_t
typedef boost::call_traits < value_t >::const_reference	const_reference_t
typedef boost::remove_const < typename boost::call_traits < value_t >::param_type > ::type	copy_t
typedef boost::intrusive_ptr < const AssignableDataSource < T > >	const_ptr
	Use this type to store a const pointer to a DataSourceBase.
typedef T	result_t
Public Member Functions
	DataObjectLockFree (const std::string &_name, const T &initial_value=T())
	Construct a DataObjectLockFree by name.
const std::string &	getName () const
	Return the name of this DataObject.
void	setName (const std::string &_name)
DataType	Get () const
	Get a copy of the data.
void	Get (DataType &pull) const
	Get a copy of the Data (non allocating).
void	Set (const DataType &push)
	Set the data to a certain value (non blocking).
DataObjectLockFree< DataType > *	clone () const
	Return a shallow clone of this DataSource.
DataObjectLockFree< DataType > *	copy (std::map< const DataSourceBase , DataSourceBase > &) const
	Create a deep copy of this DataSource, unless it is already cloned.
DataSource< T >::result_t	value () const
	Normally, value() does not trigger a get(), but for DataObjects, this is actually the sanest thing to do.
virtual DataSource< DataType > ::result_t	get () const
	Return the data as type T.
virtual void	set (typename AssignableDataSource< DataType >::param_t t)
virtual AssignableDataSource < DataType >::reference_t	set ()
	Get a reference (or null) to the value of this DataSource.
virtual void	set (param_t t)=0
	Set this DataSource with a value.
virtual AssignableDataSource < DataType > ::const_reference_t	rvalue () const
	Get a const reference (or null) to the value of this DataSource.
virtual bool	update (DataSourceBase *other)
	Update the value of this DataSource with the value of an other DataSource.
virtual CommandInterface *	updateCommand (DataSourceBase *other)
	Generate a CommandInterface object which will update this DataSource with the value of another DataSource when execute()'ed.
virtual bool	updateBlob (int protocol, const void *data)
	Updates the value of this DataSource with the value of a transportable data object.
virtual void *	server (int protocol, void *data)
	Create an object server which 'mirrors' this DataSource.
virtual bool	evaluate () const
	Force an evaluation of the DataSourceBase.
template<>
RTT_API bool	evaluate () const
	Force an evaluation of the DataSourceBase.
virtual std::string	getType () const
	Return useful type info in a human readable format.
virtual const TypeInfo *	getTypeInfo () const
	Return the Orocos type info object.
virtual std::string	getTypeName () const
	Return the Orocos type name, without const, pointer or reference qualifiers.
void	ref () const
	Increase the reference count by one.
void	deref () const
	Decrease the reference count by one and delete this on zero.
virtual void	reset ()
	Reset the data to initial values.
virtual void	updated ()
	In case the DataSource returns a 'reference' type, call this method to notify it that the data was updated in the course of an invocation of get().
virtual bool	updatePart (DataSourceBase part, DataSourceBase other)
	Update part of the value of this DataSource with the value of an other DataSource.
virtual CommandInterface *	updatePartCommand (DataSourceBase part, DataSourceBase other)
	Generate a CommandInterface object which will partially update this DataSource with the value of another DataSource when execute()'ed.
std::ostream &	write (std::ostream &os)
	Stream the contents of this object.
std::string	toString ()
	Get the contents of this object as a string.
bool	decomposeType (PropertyBag &targetbag)
	Decompose the contents of this object into properties.
bool	composeType (DataSourceBase::shared_ptr source)
	Compose the contents of this object from another datasource.
virtual void *	createBlob (int protocol)
	Creates a transportable data object with the current value of this DataSource.
virtual void *	getBlob (int protocol)
	Creates a transportable data object with the current value of this DataSource.
virtual int	serverProtocol () const
	Inspect if this DataSource is a proxy for a remote server object.
virtual void *	method (int protocol, MethodC orig, void arg)
	Create an object server which 'mirrors' this DataSource.
Static Public Member Functions
static AssignableDataSource< T > *	narrow (DataSourceBase *db)
	This method narrows a DataSourceBase to a typeded AssignableDataSource, possibly returning a new object.
static std::string	GetType ()
	Return usefull type info in a human readable format.
static const TypeInfo *	GetTypeInfo ()
	Return the Orocos type info.
static std::string	GetTypeName ()
	Return the Orocos type name, without const, pointer or reference qualifiers.
Static Public Attributes
static const unsigned int	MAX_THREADS = 8
	The maximum number of threads.
Protected Attributes
OS::AtomicInt	refcount
	We keep the refcount ourselves.

Detailed Description

template<class T>
class RTT::DataObjectLockFree< T >

This DataObject is a Lock-Free implementation, such that reads and writes can happen concurrently without priority inversions.

When there are more writes than reads, the last write will be returned. The internal buffer can get full if too many concurrent reads are taking to long. In that case, each new read will read the element the previous read returned.

     * The following Truth table applies when a Low Priority thread is
     * preempted by a High Priority thread :
     *
     *   L\H | Set | Get |
     *   Set | Ok  | Ok  |
     *   Get | Ok  | Ok  |
     *
     * legend : L : Low Priority thread
     *          H : High Priority thread
     *          Blk: Blocks High Priority thread (bad!)
     *          NA : Not allowed !
     *

Further, multiple reads may occur before, during and after a write operation simultaneously. The buffer needs readers+2*writers elements to be guaranteed non blocking.

Definition at line 480 of file DataObjectInterfaces.hpp.

Constructor & Destructor Documentation

template<class T >

RTT::DataObjectLockFree< T >::DataObjectLockFree	(	const std::string &	_name,
		const T &	initial_value = `T()`
	)			`[inline]`

Construct a DataObjectLockFree by name.

Parameters:

	_name	The name of this DataObject.
	initial_value	The initial value of this DataObject.

Definition at line 542 of file DataObjectInterfaces.hpp.

Member Function Documentation

template<class T >

DataObjectLockFree<DataType>* RTT::DataObjectLockFree< T >::clone ( ) const [inline, virtual]

Return a shallow clone of this DataSource.

This method returns a duplicate of this instance which re-uses the DataSources this DataSource holds reference to. The clone() function is thus a non-deep copy.

Implements RTT::AssignableDataSource< T >.

Definition at line 635 of file DataObjectInterfaces.hpp.

bool RTT::DataSourceBase::composeType ( DataSourceBase::shared_ptr source ) [inherited]

Compose the contents of this object from another datasource.

See also:: TypeInfo

template<class T >

DataObjectLockFree<DataType>* RTT::DataObjectLockFree< T >::copy ( std::map< const DataSourceBase *, DataSourceBase * > & alreadyCloned ) const [inline, virtual]

Create a deep copy of this DataSource, unless it is already cloned.

Places the association (parent, clone) in alreadyCloned. If the DataSource is non-copyable (for example it represents the Property of a Task ), this may be returned.

Implements RTT::AssignableDataSource< T >.

Definition at line 639 of file DataObjectInterfaces.hpp.

virtual void* RTT::DataSourceBase::createBlob ( int protocol ) [virtual, inherited]

Creates a transportable data object with the current value of this DataSource.

This does not trigger the evaluation() of this data source.

Returns:: a valid object or nill if this type is not supported.

Reimplemented in RTT::Corba::ExpressionProxy.

Referenced by RTT::Corba::CorbaDataObjectProxy< T >::Set().

bool RTT::DataSourceBase::decomposeType ( PropertyBag & targetbag ) [inherited]

Decompose the contents of this object into properties.

See also:: TypeInfo

template<>

RTT_API bool RTT::DataSource< bool >::evaluate ( ) const [inline, virtual, inherited]

Force an evaluation of the DataSourceBase.

Returns:: true on successful evaluation. If the DataSource itself contains a boolean, return that boolean.

Implements RTT::DataSourceBase.

template<typename T >

bool RTT::DataSource< T >::evaluate ( ) const [inline, virtual, inherited]

Force an evaluation of the DataSourceBase.

Returns:: true on successful evaluation. If the DataSource itself contains a boolean, return that boolean.

Implements RTT::DataSourceBase.

Reimplemented in RTT::detail::DataSourceAdaptor< From, To >, RTT::detail::DataSourceAdaptor< TFrom &, TFrom >, RTT::detail::DataSourceAdaptor< const TFrom &, const TFrom >, RTT::detail::DataSourceAdaptor< TFrom &, TFrom & >, RTT::detail::DataSourceAdaptor< TFrom, const TFrom & >, RTT::detail::DataSourceAdaptor< const TFrom, const TFrom & >, RTT::detail::AssignableDataSourceAdaptor< From, To >, RTT::detail::AssignableDataSourceAdaptor< From, const From & >, and RTT::detail::AssignableDataSourceAdaptor< To const &, To >.

Definition at line 52 of file DataSource.inl.

Referenced by RTT::detail::AssignableDataSourceAdaptor< To const &, To >::evaluate(), RTT::detail::AssignableDataSourceAdaptor< From, const From & >::evaluate(), RTT::detail::AssignableDataSourceAdaptor< From, To >::evaluate(), RTT::detail::DataSourceAdaptor< const TFrom, const TFrom & >::evaluate(), RTT::detail::DataSourceAdaptor< TFrom, const TFrom & >::evaluate(), RTT::detail::DataSourceAdaptor< TFrom &, TFrom & >::evaluate(), RTT::detail::DataSourceAdaptor< const TFrom &, const TFrom >::evaluate(), RTT::detail::DataSourceAdaptor< TFrom &, TFrom >::evaluate(), RTT::detail::DataSourceAdaptor< From, To >::evaluate(), and RTT::detail::AssignableDataSourceAdaptor< From, const From & >::get().

template<class T >

void RTT::DataObjectLockFree< T >::Get ( DataType & pull ) const [inline, virtual]

Get a copy of the Data (non allocating).

If pull has reserved enough memory to store the copy, no memory will be allocated.

Parameters:

pull

A copy of the data.

Implements RTT::DataObjectInterface< T >.

Definition at line 583 of file DataObjectInterfaces.hpp.

template<class T >

DataType RTT::DataObjectLockFree< T >::Get ( ) const [inline, virtual]

Get a copy of the data.

This method will allocate memory twice if data is not a value type. Use Get(DataType&) for the non-allocating version.

Returns:: A copy of the data.

Implements RTT::DataObjectInterface< T >.

Definition at line 574 of file DataObjectInterfaces.hpp.

References RTT::DataObjectLockFree< T >::Get().

Referenced by RTT::DataObjectLockFree< T >::Get().

virtual void* RTT::DataSourceBase::getBlob ( int protocol ) [virtual, inherited]

Creates a transportable data object with the current value of this DataSource.

This does trigger the evaluation() of this data source. Equivalent to this->evaluate(); this->createBlob();

Returns:: a valid object or nill if this type is not supported.

Reimplemented in RTT::Corba::ExpressionProxy.

template<class T >

const std::string& RTT::DataObjectLockFree< T >::getName ( void ) const [inline, virtual]

Return the name of this DataObject.

Returns:: The name

Implements RTT::DataObjectInterface< T >.

Definition at line 560 of file DataObjectInterfaces.hpp.

virtual void* RTT::DataSourceBase::method	(	int	protocol,
		MethodC *	orig,
		void *	arg
	)			`[virtual, inherited]`

Create an object server which 'mirrors' this DataSource.

Returns:: The existing server if serverProtocol() == protocol, or a new method object reference otherwise.

See also:: Operations.idl

Reimplemented in RTT::Corba::ExpressionProxy.

template<class T>

virtual AssignableDataSource<DataType>::const_reference_t RTT::DataObjectInterface< T >::rvalue ( ) const [inline, virtual, inherited]

Get a const reference (or null) to the value of this DataSource.

Getting a reference to an internal data structure is not thread-safe. DataSources which wish to protect their data from concurrent access may return the null reference with this method. All calls to rvalue() must first check whether they do not return null.

Implements RTT::AssignableDataSource< T >.

Definition at line 142 of file DataObjectInterfaces.hpp.

template<typename T >

void * RTT::AssignableDataSource< T >::server	(	int	protocol,
		void *	arg
	)			`[inline, virtual, inherited]`

Create an object server which 'mirrors' this DataSource.

Returns:: The existing server if serverProtocol() == protocol, or a new server object reference otherwise.

See also:: Operations.idl

Reimplemented from RTT::DataSourceBase.

Reimplemented in RTT::Corba::CORBAAssignableExpression< T >.

Definition at line 79 of file DataSource.inl.

References RTT::TypeInfo::getProtocol(), RTT::DataSource< T >::getTypeInfo(), and RTT::detail::TypeTransporter::server().

virtual int RTT::DataSourceBase::serverProtocol ( ) const [virtual, inherited]

Inspect if this DataSource is a proxy for a remote server object.

Returns:: 0 if it is a local DataSource, or the protocol id if it is a proxy for a remove server.

Reimplemented in RTT::Corba::AnyDataSource, RTT::Corba::CORBAExpression< T >, RTT::Corba::CORBAExpression< void >, RTT::Corba::CORBAAssignableExpression< T >, and RTT::Corba::ExpressionProxy.

Referenced by RTT::AssignableDataSource< T >::narrow(), and RTT::DataSource< T >::narrow().

template<class T>

virtual AssignableDataSource<DataType>::reference_t RTT::DataObjectInterface< T >::set ( ) [inline, virtual, inherited]

Get a reference (or null) to the value of this DataSource.

Getting a reference to an internal data structure is not thread-safe. DataSources which wish to protect their data from concurrent access may return the null reference with this method. All calls to set() must first check whether they do not return null.

Implements RTT::AssignableDataSource< T >.

Definition at line 136 of file DataObjectInterfaces.hpp.

template<class T >

void RTT::DataObjectLockFree< T >::Set ( const DataType & push ) [inline, virtual]

Set the data to a certain value (non blocking).

Parameters:

push

The data which must be set.

This method can not be called concurrently (only one producer). With a minimum of 3 buffers, if the write_ptr+1 field is not occupied, it will remain so because the read_ptr is at write_ptr-1 (and can not increment the counter on write_ptr+1). Hence, no locking is needed.

Implements RTT::DataObjectInterface< T >.

Definition at line 608 of file DataObjectInterfaces.hpp.

std::string RTT::DataSourceBase::toString ( ) [inherited]

Get the contents of this object as a string.

See also:: TypeInfo

template<class T >

bool RTT::AssignableDataSource< T >::update ( DataSourceBase * other ) [inline, virtual, inherited]

Update the value of this DataSource with the value of an other DataSource.

Update does a full update of the value, adding extra information if necessary.

Returns:: false if the DataSources are of different type OR if the contents of this DataSource can not be updated.

Reimplemented from RTT::DataSourceBase.

Definition at line 131 of file DataSource.inl.

References RTT::DataSource< T >::get().

template<typename T >

bool RTT::AssignableDataSource< T >::updateBlob	(	int	protocol,
		const void *	data
	)			`[inline, virtual, inherited]`

Updates the value of this DataSource with the value of a transportable data object.

Parameters:

any

The value to update to.

Returns:: true if any had the correct type.

Reimplemented from RTT::DataSourceBase.

Definition at line 67 of file DataSource.inl.

References RTT::TypeInfo::getProtocol(), RTT::DataSource< T >::getTypeInfo(), and RTT::detail::TypeTransporter::updateBlob().

Referenced by RTT::Corba::CorbaBufferProxy< T >::front(), RTT::Corba::CorbaDataObjectProxy< T >::Get(), RTT::Corba::ExpressionProxy::NarrowAssignableDataSource(), and RTT::Corba::ExpressionProxy::NarrowDataSource().

template<class T >

CommandInterface * RTT::AssignableDataSource< T >::updateCommand ( DataSourceBase * other ) [inline, virtual, inherited]

Generate a CommandInterface object which will update this DataSource with the value of another DataSource when execute()'ed.

Returns:: zero if the DataSource types do not match OR if the contents of this DataSource can not be updated.

Reimplemented from RTT::DataSourceBase.

Reimplemented in RTT::Corba::CORBAAssignableExpression< T >, and RTT::IndexedValueDataSource< T, Index, SetType, IPred, APred >.

Definition at line 142 of file DataSource.inl.

Referenced by RTT::Property< bool >::refreshCommand().

virtual bool RTT::DataSourceBase::updatePart	(	DataSourceBase *	part,
		DataSourceBase *	other
	)			`[virtual, inherited]`

Update part of the value of this DataSource with the value of an other DataSource.

Update does a partial update of the value, according to part, which is most likely an index or hash value of some type.

Returns:: false if the DataSources are of different type OR if the contents of this DataSource can not be partially updated.

Reimplemented in RTT::detail::AssignableDataSourceAdaptor< To const &, To >.

Referenced by RTT::detail::AssignableDataSourceAdaptor< To const &, To >::updatePart().

virtual CommandInterface* RTT::DataSourceBase::updatePartCommand	(	DataSourceBase *	part,
		DataSourceBase *	other
	)			`[virtual, inherited]`

Generate a CommandInterface object which will partially update this DataSource with the value of another DataSource when execute()'ed.

part is an index or hash value of some type.

Returns:: zero if the DataSource types do not match OR if the contents of this DataSource can not be partially updated.

Reimplemented in RTT::Corba::CORBAAssignableExpression< T >, RTT::detail::AssignableDataSourceAdaptor< To const &, To >, and RTT::IndexedValueDataSource< T, Index, SetType, IPred, APred >.

Referenced by RTT::detail::AssignableDataSourceAdaptor< To const &, To >::updatePartCommand().

std::ostream& RTT::DataSourceBase::write ( std::ostream & os ) [inherited]

Stream the contents of this object.

See also:: TypeInfo

Member Data Documentation

template<class T >

const unsigned int RTT::DataObjectLockFree< T >::MAX_THREADS = 8 [static]

The maximum number of threads.

The size of the buffer is for now statically determined, which allows for 7 readers and 1 writer (a total of 8 threads !) This is to be improved, although knowing the max number of threads in a RT application is not so hard.

Definition at line 497 of file DataObjectInterfaces.hpp.

OS::AtomicInt RTT::DataSourceBase::refcount [mutable, protected, inherited]

We keep the refcount ourselves.

We aren't using boost::shared_ptr, because boost::intrusive_ptr is better, exactly because it can be used with refcounts that are stored in the class itself. Advantages are that the shared_ptr's for derived classes use the same refcount, which is of course very much desired, and that refcounting happens in an efficient way, which is also nice :)

Definition at line 89 of file DataSourceBase.hpp.

The documentation for this class was generated from the following file:

rtt/DataObjectInterfaces.hpp

RTT::DataObjectLockFree< T > Class Template Reference [Data Transfer Ports]

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Attributes

Detailed Description

template<class T> class RTT::DataObjectLockFree< T >

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

RTT::DataObjectLockFree< T > Class Template Reference
[Data Transfer Ports]

template<class T>
class RTT::DataObjectLockFree< T >